Estimation of Stroke Etiology from Lesion Patterns on Diffusion-Weighted Magnetic Resonance Imaging in Patients with Carotid Artery Occlusive Disease

Background: Various mechanisms can be considered in ischemic stroke with internal carotid artery (ICA) occlusive diseases. We clarified the etiologic mechanisms from lesion patterns on diffusion-weighted imaging (DWI). Methods: One hundred and twenty consecutive ischemic stroke patients with ipsilateral ICA occlusive diseases were enrolled and classified into 3 groups according to the size of DWI lesions: group A, massive; group B, moderate-to-large; and group C, small. Group C was divided into 3 subgroups according to the number of lesions: C1, 1–3; C2, 4–9; and C3, 10 or more. The relationship between the DWI findings and stroke subtypes according to the TOAST classification was investigated. Results: Cardioembolism was significantly more common in groups A and B than in group C, while large-artery atherosclerosis (LAA) was more frequent in group C than in groups A and B. In group A, cardioembolism accounted for 32%, while LAA was not observed. Statistical analyses showed trends toward a higher frequency of LAA in groups C2 and C3 than in group C1. Conclusions: Mechanisms of acute stroke in ICA diseases can be simply assessed from the lesion size and number, which may be useful in considering acute therapeutic strategies.